1. Field of the Invention
The present invention relates to isolated nucleic acid sequences encoding polypeptides having pyranose oxidase activity. The invention also relates to nucleic acid constructs, vectors, and host cells comprising the nucleic acid sequences as well as recombinant methods for producing the polypeptides.
2. Description of the Related Art
Pyranose oxidases (E.C.1.1.3.10) are flavoproteins which catalyze the oxidation of several monosaccharides in the pyranose form at position C2 to produce 2-keto derivatives with the concomitant release of hydrogen peroxide. D-glucose, in its pyranose form, tends to be the preferred substrate, and is converted to 2-keto-D-glucose by pyranose oxidase. A number of other substrates can also be oxidized by the enzyme, e.g., xylose and L-sorbose which are converted to 2-keto-D-xylose and 5-keto-D-fructose, respectively. The pyranose oxidase is distinct from glucose oxidase (E.C.1.1.3.4) which catalyzes the oxidation of .beta.-D-glucose at position C1 to form D-glucono-1,5-lactone and hydrogen peroxide.
Pyranose oxidases are of widespread occurrence, but in particular, in Basidiomycota (Basidiomycete) fungi. Pyranose oxidases have been characterized or isolated, e.g., from the following sources: Peniophora gigantea, genera of the Aphyllophorales order, Phanerochaete chrysosporium, Polyporus spp., and Bierkandera adusta and Phlebiopsis gigantea. The use in baking of a pyranose oxidase from Trametes hirsuta is disclosed in WO 97/22257 (Novo Nordisk A/S) and in JP 9098710 A (Oriental Yeast Co.). DE 195 45 780 Al (Kikkoman Corp.) discloses the DNA sequence encoding an enyzme with pyranose oxidase activity at neutral pH from a strain of Coriolus versicolor.
It is an object of the present invention to provide isolated nucleic acid sequences encoding polypeptides having pyranose oxidase activity.